1. Field of the Invention
The present invention is in the fields of medicine, public health, immunology, molecular biology and virology.
2. Related Art
Addictive drug abuse disorders carry with them a number of specific, well recognized sequelae that have both societal and economic consequences. These include death, disease, violence, crime, loss of employment, reduced productivity, relationship and familial breakdown, and the spread of HIV and other sexually transmitted diseases. The economic cost to United States society from drug abuse (excluding tobacco) was an estimated $98 billion in 1992, the last year for which reliable data are available (“The economic costs of alcohol and drug abuse in the United States-1992”, National Institute on Drug Abuse). These costs include crime ($59.1 billion), premature death ($14.6 billion), impaired productivity/workplace accidents ($14.2 billion), welfare ($10.4 billion), health care ($5.5 billion), and motor vehicle accidents. These costs are borne primarily by government (46%), drug abusers and their families (44%). It is well recognized that drug abuse remains a serious problem in society. Three years after the 1992 study, in 1995, NIDA estimated drug abuse costs to the society was $110 billion.
The per se use of drugs of abuse can have deleterious effects on the user. However, it is recognized that the addictive nature of these drugs are both central to the problems associated with such drug use, and underlie the inability to treat both addicted individuals and reduce the prevalence of drug addiction in the society.
The most widely used addictive drug in the world is tobacco. Nicotine, an alkaloid derived from tobacco leaves, is the principal addictive component of tobacco. In 1999, 46.5 million adults in the United States were current smokers. Cigarette smoking is the single leading cause of preventable death in the United States. According to the Centers for Disease Control and Prevention (CDC) 430,000 annual deaths are attributable to cigarette smoking in the United States. Lung cancer, coronary heart disease, chronic lung disease, and stroke are the main causes of death. Smoking is not only dangerous to individuals, it also results in staggering societal costs. The estimated smoking-attributable cost for medical care in 1993 was more than $50 billion and the cost of lost productivity and forfeited earnings due to smoking-related disability was estimated at $47 billion per year. Thus, the total economic cost associated with nicotine addiction is greater than the combined costs for all other types of addictive drugs.
Despite recent advances in behavioral and pharmacologic treatments, the vast majority of cigarette smokers who try to quit will fail (for overview see Fiore et al. (2000) Treating tobacco use and dependence, clinical practice guideline, US Department of Health and Human Services, Public Health Service). Nicotine replacement therapy is one currently used medication, either in the form of nicotine gum, inhaler, nasal spray or transdermal patches. The efficacy of transdermal nicotine patches alone has been questioned in a placebo-controlled, double-blinded clinical trial (Joseph et al., N. Engl. J. Med. (1999), 340:1157-1158; Jorenby et al., N. Engl. J. Med. (1999) 340:685-691). Furthermore, adverse effects of nicotine gum such as mouth irritation, sore jaw muscles, dyspepsia, nausea, hiccups and paresthesia and itching, erythema, sleep disturbances, gastrointestinal problems, somnolence, nervousness, dizziness and sweating for the nicotine patch were observed. A treatment with the antidepressant bupropion can increase the abstinence rates at 12 months to about 30% (Jorenby et al., supra).
Novel approaches to the treatment and prevention of addiction, to nicotine and to other drugs, are clearly needed. Immunization strategies to modify the behavioral effects of drugs have been the subject of investigation since 1974. Both active immunization with morphine-6-hemisuccinate-BSA and passive immunization with the resultant antibodies reduced heroin self administration in rhesus monkeys (Bonese, et al. Nature 252:708-710 (1974); Killian, et al Pharmacol. Biochem. Behav. 9:347-352 (1978).) Immunization has also proven effective against cocaine addiction. Active immunization reduced the effect of subsequent cocaine administration in rats (Carrera et al Nature 379:727-730 (1995), and both active and passive immunization was demonstrated to abolish self administration (Fox et al. Nature Med 2:1129-1132 (1996)). More recently, immunization with GNC-KLH conjugate abolished self administration in cocaine-addicted rats (Carrera et al Proc. Nat. Acad Sci USA 97:6202-62061992 (2000)) and both immunization with GND-KLH conjugate or transfer of anti-cocaine monoclonal antibodies blocked cocaine effects (Carrera et al Proc. Nat. Acad Sci USA 98:1988-1992 (2001).
Antibodies have been raised against phencyclidine (PCP) and show effectiveness in reducing PCP levels in the brain, reducing behavioral effects, and show similar abilities to block the physiologic effects of PCP analogs (Hardin et al. J Pharmacol Exp Ther 285:1113-1122 (1998); Proksch et al. J. Pharmacol Exp Ther. 292:831-837 (2000)). Antibodies have also been successfully raised against methamphetamine in rats (Byrnes-Blake et al. Int Immunopharmacol 1:329-338 (2001)). U.S. Pat. No. 5,256,409 discloses a vaccine comprising a carrier protein bound to one hapten from the desipramine/imipramine class of drugs and another hapten from the nortriptyline/amitriptyline class of drugs.
Therefore, immune responses can be raised against drugs, the antibodies can block drug action, and animal models have demonstrated that vaccination is effective as a general approach to the treatment of drug abuse and addiction. It is believed that generating an immune response should block the actions of the drug by preventing it from entering the central nervous system (Carrera et al Nature 379:727-730 (1995). By reducing the rewards associated with drug use, the addicted individual is no longer motivated to consume the drug.
As the addictive effect of the drugs is caused by their action in the brain, antibodies in serum should be able to reduce drug delivery to brain. Cerny (WO 92/03163) described a vaccine and immunoserum for use against drugs of abuse. The vaccine consisted of a hapten bound to a carrier protein. Also disclosed therein was the production of antibodies against drugs, and the use of these antibodies in the detoxification of one who has taken the drug.
Nicotine, cocaine, heroin and most drugs of abuse are haptens, which are not immunogenic. Coupling of haptens to protein carriers typically enhances their immunogenicity.
Several different nicotine haptens, carriers and methods of coupling have been described. Matsushita et al. (Biochem. Biophys. Res. Comm. (1974) 57, 1006-1010) and Castro et al. (Eur. J. Biochem. (1980) 104, 331-340) prepared nicotine haptens conjugated to bovine serum albumin (BSA) via a linker at the 6-position of the nicotine. Elsewhere, Castro et al. (Biochem. Biophys. Res. Commun. (1975) 67, 583-589) disclosed two nicotine albumin conjugates: N-succinyl-6-amino-(+/−)-nicotine-BSA and 6-(sigma-aminocapramido)-(+/−)-nicotine-BSA. Noguchi et al. (Biochem. Biophys. Res. Comm. (1978) 83, 83-86) prepared a nicotine-BSA conjugate with nicotine conjugated at the 1-position of the nicotine. Langone et al. (Biochemistry (1973) 12, 5025-5030 and Meth. Enzymol. (1982) 84, 628-640) prepared the hapten derivative O-succinyl-3′-hydroxymethyl-nicotine and conjugated it to bovine serum albumin and keyhole limpet hemocyanin. According to the procedures of Langone et al. (supra), Abad et al. (Anal. Chem. (1993) 65, 3227-3231) synthesized the nicotine hapten 3′-(hydroxymethyl)-nicotine hemisuccinate and coupled it to bovine serum albumin for immunization of mice to produce monoclonal antibodies to nicotine. Isomura et al. (J. Org. Chem. (2001) 66, 4115-4121) provided methods to synthesize nicotine conjugates linked to the 1′-position of nicotine, which were coupled to keyhole limpet hemocyanin (KLH) and BSA. The conjugate to KLH was used to immunize mice and to produce monoclonal antibodies against nicotine. Svensson et al. (WO 99/61054) disclosed nicotine-haptens conjugated via the pyridine ring and further disclosed a nicotine-hapten conjugated to KLH and the induction of nicotine-specific IgG antibodies using such conjugates. When administered in the presence of complete Freund's adjuvant, nicotine-specific ELISA titres of 1:3000 to 1:15500 were measured, while in the absence of Freund's adjuvant titres of 1:500 to 1:3000 were detected. Ennifar et al. (U.S. Pat. No. 6,232,082) disclosed nicotine haptens coupled via the pyrrolidine ring and disclosed a nicotine-hapten conjugated to recombinant Psuedomonas aeruginosa exotoxin A (rEPA) and the induction of nicotine-specific IgG antibodies when the conjugates were administered in the presence of complete Freund's adjuvant. Swain et al. (U.S. Pat. No. 5,876,727) disclosed the coupling of a nicotine hapten to BSA and the induction of nicotine-specific IgG antibodies in mice when the conjugates were given in a mixture with complete Freund's adjuvant.
The feasability of a vaccination against nicotine has been shown in principle (Hieda et al., J. Pharm. Exp. Ther. (1997) 283, 1076-1081; Hieda et al., Psychopharm. (1999), 143, 150-157; Hieda et al., Int. J. Immunopharm. (2000) 22, 809-819; Pentel et al., Pharm. Biochem. Behav. (2000), 65, 191-198, Malin et al, Pharm. Biochem. Behav. (2001), 68, 87-92). Covalent conjugates of nicotine with KLH or rEPA were produced and injected into mice or rats in the presence of complete Freund's adjuvant, and induced nicotine-specific IgG antibodies. Vaccine efficacy was demonstrated by several different ways. After challenge with nicotine, more nicotine remained bound in serum and nicotine concentrations were lower in the brain in the nicotine-KLH or nicotine-rEPA immunized groups of rats compared to the control group immunized with carrier alone. Immunization also reduced the psychopharmacological activity associated with nicotine, as immunized animals were also less susceptible to the effect of nicotine on locomoter activity, dopamine release (Svensson et al. WO 99/61054) and relief of nicotine withdrawal symptoms.
The above art demonstrates the efficacy of vaccine compositions containing complete Freund's adjuvant to induce immune responses against nicotine. Complete Freund's adjuvant is one of the most potents adjuvants available, however because of its side effects its use is not approved for humans. Therefore, there exists a need for vaccine compositions able to induce strong immune responses against nicotine without the use of complete Freund's adjuvant. Further, while BSA has been used successfully as a carrier in animal models it may not be appropriate for use in human vaccine compositions because of the risk of adverse reactions such as the risk of transmitting prion disease (variant Creutzfeldt-Jakob disease). A further challenge to the development of an effective vaccine against nicotine is the need for an immune response able to rapidly decrease nicotine available for absorption by the brain. Nicotine from cigarettes is taken up by mucosal surfaces especially in the mouth and lungs and transported via the blood to the brain. If nicotine-specific antibodies are to be successful in reducing nicotine delivery to brain, they will have to overcome the very high arterial nicotine concentration that is presented to brain within seconds of inhalation (Hieda et al., 1999, supra). Therefore, high concentrations of nicotine-specific antibodies in the blood, which are mainly of the IgG subtype are needed. In mucosal surfaces IgA antibodies are the primary subtype. Accordingly, in addition to the antibodies in blood, nicotine-specific antibodies of the IgA subtype in the lung would be beneficial for neutralizing nicotine inhaled during smoking before it begins circulating in the blood.
Cholera toxin, a known carrier protein in the art, can induce IgA antibodies, in particular after intranasal administration. Cholera toxin can also act as an adjuvant, eliminating the need for complete Freund's adjuvant in a vaccine composition. However, when cholera toxin is administered as a mucosal adjuvant it stimulates a predominantly TH2-type immune response with increased interleukin-4 levels and associated increments in total and specific IgE antibody levels (Yamamoto et al., (1997) Proc. Natl. Acad. Sci USA 94, 5267-5272). After nasal immunization in the presence of cholera toxin, IgE-associated inflammatory reactions developed within the lungs of mice (Simecka et al., (2000) Infect. Immunol. 68, 672-679, Hodge et al., (2001) Infect. Immunol., 69, 2328-2338). Despite the promise of intranasal immunization in the presence of cholera toxin, there is also the potential to develop adverse immunopathological reactions characterized by pulmonary airway inflammation (Hodge et al., (2001) Infect. Immunol., 69, 2328-2338).
Therefore, there exists a need for carrier systems able to stimulate immune responses against hapten without the use of toxic adjuvants, without the use of poorly tolerated carrier proteins and, in certain situations, without stimulation of potentially pathologic TH2 immune responses. Novel carrier systems meeting these specifications can be used towards the formation of novel conjugates and compositions suitable for the treatment of addiction, among other conditions, for which there is currently an urgent need.